Hi all, I'm not sure as to whether the HF Horn on my Line 6 LD400 Pro has gone or not? This is a switchable horn via a small push button on the front of the amp, I seem to recall it being easy to discern the difference between the horn being switched on or not but am now struggling to hear any difference at all, even at close range. If you put your ear next to the horn you can definitely hear a slight hiss from it when you switch it on. I always thought with horns that they either work or they don't, so perhaps it isn't a horn issue at all but a problem on the crossover in the amp, i.e. the horn is working but is not receiving the high frequencies from the amp itself? I presume that if I am correct in saying that horns either work or they don't then a simple battery test across the terminals should verify whether it's gone or not for sure. I know that Line 6 have a bit of a history for having connections work loose or disconnect completely, so that is another route I'm considering if the horn appears to be ok. Has anyone else experienced similar issues, not necessarily with the LD400 but on any other amps? I would be grateful in receiving any advice on this. Cheers.